We published in May 10, 2022 a retrospective cohort study comparing the post-radiotherapy (post-RT) hemoglobin levels between patients with breast cancer who underwent intensity-modulated radiotherapy (IMRT) and those who underwent three-dimensional conformal radiotherapy (3D-CRT) in the Radiation Oncology Section of the Department of Radiological and Imaging Sciences of Southern Philippines Medical Center (ROS DORIS-SPMC) from October 2018 to March 2019. It came to our knowledge that the IMRT planning that was done on the patients included in our study was different from the IMRT planning that is currently being done since late 2020. Prior to late 2020, ROS DORIS-SPMC had been implementing forward-planned IMRT, wherein the weight of the multileaf collimator (MLC) segment was preselected at fixed values. In late 2020, ROS DORIS-SPMC started implementing inverse-planned IMRT, wherein the appropriate weights of the MLC segments are determined by an inverse optimization algorithm that creates a more uniform dose distribution throughout the target. Inverse-planned IMRT improves the dose homogeneity within the entire 3D-breast volume, while forward-planned IMRT mainly improves the dose distribution on the inframammary fold.1 Compared to 3D-CRT, however, forward-planned IMRT improves target homogeneity, albeit to a lesser degree than the homogeneity produced by the inverse technique.2 In the original article, we also stated that, for both IMRT and 3D-CRT, each dose fraction is given weekly within a span of 7 to 8 months. We recently confirmed that, among patients with breast cancer, each dose fraction of IMRT or 3D-CRT is given daily within a span of 33 days—28 days for conventional dose and 5 days for boost dose. In this corrigendum, we specify that the IMRT protocol used among the patients in our study was forward-planned IMRT, with all dose fractions given daily for 33 consecutive workdays, excluding weekends and holidays. We also describe here the original statements that we changed or removed because they have become irrelevant in light of the corrections. The table below shows the list of corrections.
Radiotherapy, Intensity-Modulated ; Radiotherapy, Conformal

BACKGROUND: Radiotherapy (RT) to the chest or other large areas of the body may cause bone marrow suppression, resulting in anemia and other changes in blood cell counts. OBJECTIVE: To compare the post­RT hemoglobin levels between patients who underwent forward­ planned intensitymodulated radiotherapy (FPIMRT) and those who underwent three­dimensional conformal radiotherapy (3D­CRT). DESIGN: Retrospective cohort study SETTING: Department of Radiological and Imaging Sciences, Southern Philippines Medical Center, Davao City, from October 2018 to March 2019. PARTICIPANTS: 94 women with invasive ductal carcinoma, aged 29 to 75 years, who received at least 28 fractions (with or without boost dose) of either 3D­CRT or FPIMRT. MAIN OUTCOME MEASURES: Mean hemoglobin counts and anemia within 4 weeks post­RT. MAIN RESULTS: Of the 94 women, 62 (65.96%) underwent 3D­CRT, and 32 (34.04%) underwent FPIMRT. The proportion of patients with left­sided tumors was significantly higher in the FPIMRT group than in the 3D­CRT group. The baseline hemoglobin levels (12.60 ± 1.04 g/dL for 3D­CRT vs 12.49 ± 0.80 g/dL for FPIMRT; p=0.5994) and the mean changes in hemoglobin count from baseline (­0.11 ± 0.72 g/dL for 3D­CRT vs ­0.18 ± 0.67 g/dL for FPIMRT; p=0.6707) were both comparable between the two groups. The proportions of patients with anemia within four weeks post­RT were also comparable between the two groups (13/62, 20.97% for 3D­CRT vs 8/32, 25.00% for FPIMRT; p=0.6565). Left­sided tumors were significantly associated with post­RT anemia (unadjusted OR 2.87; 95% CI 1.00 to 8.22; p=0.0498), even after controlling for type of RT technique (adjusted OR 3.15; 95% CI 1.01 to 9.87; p=0.0484). CONCLUSION After RT, the mean hemoglobin levels of patients with breast cancer who underwent 3D­CRT were comparable with those of patients who underwent IMRT. The type of RT technique was not significantly associated with the occurrence of post­RT anemia in these patients.